Viro3DObject not load .mtl file

[Ayzekberk]

<Viro3DObject
  source={require('../assets/ARAssets/3dObjects/untitled_obj.obj')}
  resources={[
    require('../assets/ARAssets/3dObjects/untitled.mtl'),
  ]}
  lightReceivingBitMask={3}
  position={[0, 0, 0]}
  scale={[0.5, 0.5, 0.5]}
  rotate={[0, 0, 0]}
  type="OBJ"
/>

Following pseudocode is my 3dobject. I also added rn-cli.config.js file correctly in my project root folder under index.js and there is extention named .mtl exist.
I have also ambientlight properly on top of 3DObject. But my object still seems white. I already checked .mtl file from 'blender' and 'FBX Review'. So what went wrong i can't find